Method of handling context during scaling with a map display

ABSTRACT

A method for displaying a zooming operation on a display screen of a computing platform. The method includes retrieving data from a geographic data storage system, possibly located on another system, displaying a starting image that shows geographic features at a first scale with a first level of detail and then displaying an ending image that shows the same geographic features at a second scale with a second level of detail. Between the displaying of the starting image and the displaying of the ending image, at least one intermediate image is displayed. The intermediate image combines two component images of at least some of the same geographic features shown in the starting or ending image. The two component images in the intermediate image are at the same scale and are registered with respect to each other so that the same geographic features represented in the two component images coincide. One of the two component images in the intermediate image includes at least a portion of the starting image and is formed using data from a first layer of a geographic database. The other of the two component images in the intermediate image is formed using data from a second layer of the geographic database.

BACKGROUND OF THE INVENTION

The present invention relates to the presentation of map information ona display screen of a computing device, and more particularly, thepresent invention relates to a way to improve the presentation of mapinformation on a display screen of a computing device when a user zoomsin or out.

There are various computing platforms that graphically display maps ofgeographic areas. For example, some in-vehicle navigation systemsinclude a display screen upon which a map of a geographic area can bedisplayed graphically. In addition, by using appropriate softwareapplications, maps can also be displayed on general purpose computingplatforms, such as personal computers and personal digital assistants.

Some computing platforms and applications that display maps graphicallyinclude features that allow a user to interact with the map. Varioustypes of user interaction may be supported. Among the features that maybe supported is the ability to zoom in or out. When a user zooms in on amap, a sub-portion of the originally displayed map is selected. The usermay operate a pointing device for this purpose. Then, a new map isgraphically displayed. The new map corresponds to the geographic area ofthe selected sub-portion of the originally displayed map. The new map isat a larger scale than the originally displayed map so that new mapfills the same area on the display screen of the computing device onwhich the originally displayed map had been shown.

When a user zooms out on a graphically displayed map, the new map is ata smaller scale that the previously displayed map. The new mapcorresponds to a geographic area that is larger than the geographic areathat corresponds to the previously displayed map such that thegeographic area that corresponds to the previously displayed map is onlya sub-portion of the geographic area that corresponds to the new map.

Maps shown at different scales on display screens may include differentlevels of detail. This is done in order to make it easier for a user toread and understand the information presented on the map. For example,large-scale maps may include more detail (e.g., all the streets andother cartographic features may be displayed) whereas small-scale mapsmay include less detail (e.g., secondary streets and minor features maybe omitted). If secondary streets and minor features were not omitted ona small-scale map, the display would contain so much information that auser may find it difficult to understand.

Because maps at different scales are associated with different levels ofdetail, a lower level layer of map information may become visible ordisappear when a user is zooming in and out on a map. The suddenappearance or disappearance of an entire level of map information maysometimes be confusing to the user. In addition, geographic features maybe represented differently at different levels of detail. For example,on a large scale map (i.e., a map with a high level of detail), a roadon which the lanes are separated by a median may be represented by twoseparate lines—one line representing the lanes on one side of the medianand the other line representing the lanes on the other side of themedian. However, on a small scale map (i.e., a map with a low level ofdetail), a road on which the lanes are separated by median may berepresented by only a single line. This change in the appearance ofrepresented features that occurs when zooming in and out on a map canalso be confusing to a user. For example, if an area or intersectionchanges shape significantly when the scale is changed, the user may losehis/her point of reference on the map, i.e., he/she may become unsurewhere on the map it was that he/she was viewing. This can lead torepeated zooms in and then out while the user tries to determine whichroads and features remain the same across the transition between levelsof detail.

Accordingly, there is a need for an improved way to represent mapfeatures when zooming in and out.

SUMMARY OF THE INVENTION

To address these and other objectives, the present invention comprises amethod for representing geographic features when a map display is zoomedin or out. The method includes displaying a starting image that showsgeographic features at a first scale with a first level of detail andthen displaying an ending image that shows the same geographic featuresat a second scale with a second level of detail. Between the displayingof the starting image and the displaying of the ending image, at leastone intermediate image is displayed. The intermediate image combines twocomponent images of at least some of the same geographic features shownin the starting or ending image. The two component images in theintermediate image are at the same scale and are registered with respectto each other so that the same geographic features represented in thetwo component images coincide. One of the two component images in theintermediate image includes at least a portion of the starting image andis formed using data from a first layer of a geographic database. Theother of the two component images in the intermediate image is formedusing data from a second layer of the geographic database.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a computing platform that incorporatesan embodiment of a feature for a map display that provides contextduring scaling.

FIG. 2 is a diagram of the database in FIG. 1 and shows an arrangementfor organizing the database into layers.

FIG. 3 is an illustration of the display screen of FIG. 1 with a firstmap image of a geographic feature displayed thereon.

FIG. 4 is an illustration of the display screen of FIG. 1 with anintermediate map image of the same geographic feature as shown in FIG. 3displayed thereon.

FIG. 5 is another illustration of the display screen of FIG. 1 withanother intermediate map image of the same geographic feature as shownin FIGS. 3 and 4 displayed thereon.

FIG. 6 is another illustration of the display screen of FIG. 1 with yetanother intermediate map image of the same geographic feature as shownin FIGS. 3-5 displayed thereon.

FIG. 7 is another illustration of the display screen of FIG. 1 withstill another intermediate map image of the same geographic feature asshown in FIGS. 3-6 displayed thereon.

FIG. 8 is an illustration of the display screen of FIG. 1 with a finalmap image of the same geographic feature as shown in FIGS. 3-7 displayedthereon after zooming out to a desired scale.

FIG. 9 is a block diagram showing components in an embodiment wherebydata for providing context while scaling are downloaded from a server toa client platform.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS I. Overviewof Computing Platform and Geographic Database

FIG. 1 shows a computing platform 10. The computing platform 10 may bean in-vehicle navigation system, a personal navigation system, apersonal computer, a personal digital assistant, or other device. Thecomputing platform 10 may be part of a network or may be a standalonedevice.

Associated with the computing platform is a geographic database 14. Thegeographic database 14 may be located locally with the computingplatform 10 or may be located remotely from the computing platform 10.If the geographic database 14 is located remotely from the computingplatform 10, the data in the geographic database 14 may be provided tothe computing platform 10 via a network or other type of communicationssystem. The network or other type of communications system may bewireless, land-based, or a combination of both wireless and land-based.The network may include the Internet.

The geographic database 14 includes data from which maps can begraphically rendered. Formats for organizing and accessing a geographicdatabase that includes data from which maps can be graphically renderedare disclosed in U.S. Pat. Nos. 5,968,109 and 6,047,280, the disclosuresof which are incorporated herein by reference.

Associated with the computing platform 10 is a program 18 that uses datafrom the geographic database 14 to render maps graphically on a displayscreen 12 of the computing platform 10. There are various ways toimplement a program that uses data from a geographic database to rendermaps graphically. For example, ways to display maps using data from ageographic database are disclosed in U.S. Pat. Nos. 6,092,076 and6,163,749, the disclosures of which are incorporated herein byreference.

As mentioned above, when displaying maps at different scales, it may bepreferred to provide the maps with different levels of detail. In orderto facilitate the presentation of maps at different levels of detail,data that represent geographic features may be organized into layers.FIG. 2 is a diagram illustrating an organization of the geographicdatabase 14 into layers. In the embodiment of FIG. 2, the geographicdatabase is organized into layers based on a rank associated with therepresented features. The lowest rank (e.g., 0) is associated with thosefeatures that are represented only when the finest level of detail isdesired. In the case of roads, the lowest rank may be associated withside streets and alleys. On the other hand, the highest rank (e.g., 4)is associated with the most important features, i.e., those that wouldbe displayed even at the coarsest level of detail. In the case of roads,the highest rank may be associated with expressways and major arterialroads.

When data representing geographic features are organized into layers,the lowest layer (e.g., 0) includes data representing geographicfeatures of all ranks (e.g., 0-4). A highest layer (e.g., 4) includesdata representing geographic features of only the highest rank (e.g.,4). Each other layer includes only those data that represent thosegeographic features of the associated rank and higher ranks. Forexample, layer 2 includes data that represent geographic features havingranks 2, 3 and 4. Layer 2 excludes data that represents geographicfeatures of ranks 0 and 1.

As shown in FIG. 2, these layers can exist as separate collections ofthe geographic data. When a navigation function, such as map display,requires geographic data with a high level of detail, a lower layer isaccessed and used. On the other hand, when a navigation functionrequires geographic data with a low level of detail, a higher layer isaccessed and used.

In an alternative embodiment, layers can be implemented logically with asingle collection of the geographic data. The single collection wouldinclude all the data of all the ranks, i.e., similar to layer 0 in FIG.2. When a navigation function requires geographic data with a low levelof detail, geographic features having higher ranks are suppressedlogically. The logical suppression of higher ranked data is performedusing a software program.

II. Context During Scaling Feature

In accordance with a first embodiment, the map display program (e.g., 18in FIG. 1) implements a feature whereby a user is presented with contextinformation when changing scale, e.g., zooming, with a map beingdisplayed. This context information takes the form of one or moreintermediate (or transitional) displays of map information between theoriginal map display (i.e., the map being shown before the userinitiates a zooming operation) and the final map display (i.e., the mapbeing shown when the zooming operation is completed). Each intermediatedisplay of map information includes at least portions of two separatelayers of map information. The data from these two separate layers ofmap information are on the screen at the same scale at the same time andoverlaid so that the represented features coincide. In at least one ofthe intermediate displays, the two layers of map information include thelayer used for the original map display. The other layer may be thelayer used for the final map display, or if there are one or more layersof map information with levels of detail between the level used for theoriginal map display and the level used for the final map display, theother layer included in the intermediate display with the layer used forthe original map display may be one of these intermediate layers. Byshowing an intermediate image that includes both the original map dataand data from another layer (either the layer used for the final mapdisplay or another layer between the layer used for the original displayand the final display), the user is better able to observe therelationship between the original map display and the final map display.

In one embodiment, at least one intermediate image is provided for eachtransition between adjacent layers when zooming. For example, if a userzooms from a map display formed using data from layer 0 to a map displayformed using data from layer 4, there are four intermediate images. Afirst intermediate image shows at least portions of layer 0 and layer 1at the same time, a second intermediate image shows portions of layer 1and layer 2 at the same time, a third intermediate image shows portionsof layer 2 and layer 3 at the same time, and a fourth intermediate imageshows portions of layer 3 and layer 4 at the same time. In analternative embodiment, some of these intermediate images may be omittedor combined. For example, an intermediate image may be formed using datafrom three separate layers at the same time.

Each intermediate image of map information includes component imagesformed from portions of at least two separate layers of map information.The component images are on the screen at the same scale at the sametime and overlaid so that the represented features coincide. In at leastone of the intermediate images, the two layers of map informationinclude the layer used for the original map display.

In order to improve presentation of the map information in anintermediate image when data from two separate layers are on the screenat the same time, the data from one of the layers may be presented at areduced level of color saturation (e.g., a percentage grayscale) or witha level of transparency. For example, if an intermediate image includesdata from layer 0 which had been used for the original map display anddata from layer 1, the data from layer 1 may be shown at 50% colorsaturation (e.g., 50% grayscale). If several intermediate images arepresented for this transition (i.e., layer 0 to layer 1), eachsuccessive intermediate image would show the layer 0 data with lowerlevels of color saturation (e.g., 100% to 60% to 20%) while the colorsaturation of the layer 1 data would increase in each successiveintermediate image (e.g., 20% to 40% to 60%).

According to another alternative, the intermediate displays may includeboth decreasing levels of color saturation (or increasing transparency)for the data obtained from one layer and increasing levels of colorsaturation (or decreasing transparency) for data obtained from thesuccessive layer. Using any of these alternatives, a gradual fadingeffect can be implemented. According to another alternative, theintermediate images can be more gradual to increase the fading effect.

EXAMPLE

An example of an implementation of an embodiment of the map displayfeature that provides context during scaling is shown in FIGS. 3-8. FIG.3 shows an illustration of a geographic feature on the display screen 12of a computing platform (10 in FIG. 1). The geographic feature is acomplex highway interchange. The illustration in FIG. 3 is renderedusing data from the geographic database (14 in FIGS. 1 and 2). The dataused to form the map display of FIG. 3 is obtained from layer 0 of thegeographic database (14 in FIGS. 1 and 2). In the illustration in FIG.3, there are some rank 0 roads and ramps, a rank 1 road crossingeast-west, and a rank 3 double digitized highway. In FIG. 3, the datarepresenting this complex interchange is shown at a scale that is zoomedin far enough to see everything. All the roads are present and fullyvisible.

When the image of FIG. 3 is being displayed on the display screen 12,the user implements a zooming operation, e.g., zooms out. The user mayinitiate the zooming operation by manipulating the user interface of thecomputing platform (10 in FIG. 1). For example, the user may use apointing device, such as a mouse, to select an area on the display andindicate that zooming out is desired. When the user initiates thezooming operation, the program 18 obtains data from the geographicdatabase 14 that corresponds to the same geographic area, but at asmaller scale.

FIGS. 4-7 represent successive intermediate map images and FIG. 8represents the final map display, i.e., the map image at the scaledesired by the user when zooming out is fully completed. In FIG. 4, afirst intermediate image shows layer 0 and layer 1 data. The layer 0data and the layer 1 data are on the screen at the same time. The layer0 data and the layer 1 data are adjusted to the same scale andregistered with respect to each other so that the same featuresrepresented by each layer coincide (or overlap). The layer 0 data isshown at a 50% color saturation (50% grayscale) and the layer 1 data isshown at full color saturation (100% black).

FIG. 5 shows a second intermediate image of the same geographic feature(i.e., the intersection). The image in FIG. 5 is displayed after theimage of FIG. 4. The image of FIG. 5 is zoomed out even farther from theimage in FIG. 4. Layer 0 data is now present only at 20% grayscale.

FIG. 6 shows a third intermediate image of the intersection. The imagein FIG. 6 is displayed after the image of FIG. 5. The image of FIG. 6shows the intersection zoomed out to where layer 2 is the presentationlayer at this scale. The only layer 2 information corresponding to thisfeature is the two lines of the double digitized highway. According tothis embodiment, the layer 1 road running east-west is shown in 50%grayscale. This helps the map user retain an idea of where on thehighway a point is. The user can relate a location to before or afterthe overpass. At this scale, the generalized layer 3 version of thehighway in gray is beginning to appear. This prepares the map user forthe scale at which the two lines representing the highway will turn intoa single line.

FIG. 7 shows another intermediate image. In the intermediate image shownin FIG. 7, data from layer 3 shows the highway as a single line. Thisdata from layer 3 is shown at 100% color saturation. The intermediateimage shown in FIG. 7 also includes data from layer 2 that shows thehighway as a pair of double lines. The data from layer 2 is shown at 50%color saturation and appears in the intermediate image of FIG. 7 as thingray borders.

FIG. 8 shows the final map display with the image of the geographicfeature fully zoomed out to the scale desired by the user. In FIG. 7,the highway is shown as a single thin line with 100% color saturationusing only data from layer 3.

III. Alternatives

A. Scalable Vector Graphics (SVG)

Scalable Vector Graphics (SVG) is a proposed standard for web graphicsthat is being developed by the W3 consortium. SVG envisions a graphicsfile format with multiple layers of graphics that are developed frompolygons, similar to Macromedia Flash or Postscript graphics. Animationis possible with JavaScript code that is part of the graphics file.Transparency of graphics elements are also part of the SVG model.Support for SVG may be included in future browsers, much like supportfor JPEG and GIF is today.

One of the applications for the SVG format is the display of maps. SVGprovides the ability to download maps (as vectors) that can be zoomedand possibly panned without further interaction with the server, atleast until more data is needed. Although the SVG format may be helpfulfor displaying some maps, the SVG format has some limitations. An SVGmap with full layer 0 detail for a geographic area, along with contexthigher level information, would look very cluttered in the detail areawhen zoomed out. Such a map may also be slow to display. In addition,the display may include detail that is too small to see. Thesedifficulties can be addressed using an embodiment of the disclosed mapdisplay feature that provides context during scaling.

According to one embodiment, a user operates a client-computing platformto request data from a server for a map of a location. The user mayaccess the server over a network, such as the Internet. The userrequests the data in a vector format (such as SVG). The server sends theuser a file that contains multiple layers of data. The file would beabout four times the size of an SVG map that only showed the data for asingle layer at one scale. On the client computing platform, the useruses a viewer capable of viewing smooth scale changes, such as a SVGviewer, to view the downloaded data as a map image. Included with thedownloaded file would be a routine or script that could be used in theSVG viewer to adjust layer transparency depending upon zoom layer. Theroutine or script may be written in JavaScript code, for example. FIG. 9illustrates components used to implement this embodiment.

According to another embodiment, a user operates a client computingplatform to request data from a server for a map of a route. The serversends the user a file that contains multiple layers of data for forminga map for the route. The map for a route includes a nesting set of stripmaps centered around the route. Each layer included in the downloadedfile would show an area around the route appropriate to the displayscale of the layer. As described above, the user uses a viewer, such asan SVG viewer, to view the downloaded data as a map image. The usercould zoom in and out of the route, pan along the route and save thedownloaded file to transfer to another computer.

Using these embodiments, a user can download a map file that will lookattractive at any scale. By using the context during scaling feature,the user may find the map data easier to use and understand whenperforming a zooming operation.

B. Smooth Zooming Versus Discrete Stages Zooming

As stated above, when a user operates the map display for a zoomingoperation, the scale of the map changes. The map scale may change indiscrete stages or alternatively, the map scale may change gradually,i.e., in stages so small that it appears to the user to be smooth.Embodiments of the context during scaling feature can be used withzooming that occurs in discrete stages or smoothly.

C. Alternative File Formats

It was mentioned above how embodiments of the map display feature thatprovides context during scaling can be used with vector formats, such asSVG. Embodiments of the map display feature that provides context duringscaling can also be used with other file formats, including staticformats like JPEG or GIF. If a map is provided in a file format, such asa GIF file format or a JPEG file format, the map can be displayed withan appropriate viewer for such a format. A routine included with thedownloaded data would provide for displaying the images over one anotherwith the appropriate transparency.

D. Alternative Colors

In some of the embodiments described above, when data from two differentlayers are shown at the same time on the display screen, the data fromone of the layers is shown at a reduced level of color saturation. Insome of the embodiments, this reduced level of color saturation is ashade of gray. However, the display of geographic features is notlimited to black or gray. In alternative embodiments, the geographicfeatures can be shown in any color, such as blue, red, etc. Geographicfeatures shown in these colors can be shown with reduced levels of colorsaturation (or transparency), as appropriate, when shown in intermediateimages with any of the above described embodiments.

IV. Advantages

The disclosed embodiments provide several advantages. According to thedisclosed embodiments, different layers of data can be scaled toappropriate levels of accuracy on the server. When these data aredownloaded to a client platform, the data are displayed only withinappropriate ranges of scales. In this way, the data are not displayedwith unintelligible detail or large overly heavy lines. Each layer canhave its own scaling equation.

It is intended that the foregoing detailed description be regarded asillustrative rather than limiting and that it is understood that thefollowing claims including all equivalents are intended to define thescope of the invention.

We claim:
 1. A method for displaying a zooming operation on a displayscreen of a client computing platform, the method comprising: obtaininga collection of data for displaying map images of geographic features;using said data to display on the display screen a first image showinggeographic features at a first scale with a first level of detail andthen to display on the display screen a second image showing the samegeographic features at a second scale with a second level of detail,wherein the second scale is different from the first scale; and betweenthe displaying of the first image and the displaying of the secondimage, displaying on the display screen an intermediate image thatcombines two component images showing at least some of the samegeographic features, wherein the two component images in theintermediate image arm at the same scale, wherein the two componentimages in the intermediate image are registered so that the samegeographic features represented in the two component images coincide,and wherein one of the two component images in the intermediate imageincludes at least a portion of the first image and is formed using datafrom a first layer of a geographic database and the other of the twocomponent images in the intermediate image is formed using data from asecond layer of the geographic database.
 2. The method of claim 1wherein at least one of the two component images in the intermediateimage is displayed at a less than full color saturation.
 3. The methodof claim 1 wherein the second image is formed using data from the secondlayer of the geographic database.
 4. The method of claim 1 wherein theone of the two component images in the intermediate image graduallyfades out.
 5. The method of claim 1 wherein the other of the twocomponent images in the intermediate image gradually fades in.
 6. Themethod of claim 1 wherein at least some geographic features representedby the first image are displayed differently in the second image.
 7. Themethod of claim 1 wherein the scale used for the intermediate imagecorresponds to the first scale.
 8. The method of claim 1 wherein thescale used for the intermediate image corresponds to the second scale.9. The method of claim 1 further comprising the steps of: obtaininggeographic data from the first layer of the geographic database todisplay the first image; and obtaining geographic data from the secondlayer of the geographic database to display the intermediate image. 10.The method of claim 1 wherein at least one of the two component imagesin the intermediate image is displayed with transparency.
 11. The methodof claim 1 wherein the first image and the second image are displayedusing the Scalable Vector Graphics standard.
 12. The method of claim 1wherein the first image and the second image are displayed in anInternet browser.
 13. The method of claim 1 wherein the computingplatform is a vehicle navigation system.
 14. The method of claim 1wherein the step of obtaining comprises downloading the collection ofdata from a server.
 15. A method of providing context while zooming amap display on a client computing platform, the method comprising:obtaining data from a first layer of a geographic database to representgeographic features at a first scale in a first image; displaying saidfirst image on the display screen; using data from a second layer of thegeographic database to represent at least some of the geographicfeatures at a second scale in a second image, wherein the second scaleis different from the first scale; displaying said second image on thedisplay screen after displaying said first image; combining data from atleast two separate layers of the geographic database to represent atleast some of the geographic features in a third image, wherein the twoseparate layers include at least one of the first layer and the secondlayer, and wherein the third image is separate from the first image andthe second image; displaying said third image on the display screenafter displaying said first image and before displaying the secondimage.
 16. The method of claim 15 further comprising: prior to the stepof using data from the first layer of the geographic database torepresent geographic features at the first scale in the first image,downloading the data used to represent the geographic features in thefirst image, the second image and the third image from a server.
 17. Amethod of providing context while zooming a map display on a clientcomputing platform, the method comprising: obtaining data from a firstlayer of a geographic database located on a server to representgeographic features at a first scale in a first image; displaying saidfirst image on the display screen; using data from a second layer of thegeographic database located on the server to represent at least some ofthe geographic features at a second scale in a second image, wherein thesecond scale is different from the first scale; displaying said secondimage on the display screen after displaying said first image; combiningdata from at least two separate layers of the geographic database torepresent at least some of the geographic features in a third image,wherein the two separate layers include at least one of the first layerand the second layer; displaying said third image on the display screenafter displaying said first image and before displaying the second imageprior to the step of using data from the first layer of the geographicdatabase to represent geographic features at the first scale in thefirst image, downloading the data used to represent the geographicfeatures in the first image, the second image and the third image fromthe server; and downloading a routine from the server that adjusts layertransparency depending upon zoom layer.
 18. A method of presenting a mapon a display screen of a client computing platform, comprising the stepsof: sending a request from the client computing platform to a server formap data; on the client computing platform, receiving map data from theserver, wherein the map data includes data from at least two separatelayers, wherein each of said layers represents geographic features at adifferent level of detail; using the map data from one of said layers topresent on a display screen of the client computing platform a first mapimage that represents geographic features in a first geographic area;initiating a zooming operation on the client computing platform; andpresenting an intermediate image on the display screen of the clientcomputing platform, wherein the intermediate image includes at least aportion of the first map image and also includes a second map image ofthe same geographic features shown in the portion of the first map imageusing data from another of said layers, wherein tile same geographicfeatures shown by the first map image and the second map image in theintermediate image coincide.
 19. The method of claim 18 wherein the stepof presenting is performed by an SVG viewer.
 20. The method of claim 18further comprising: on the client computing platform, receiving aroutine from the server along with the map data, wherein the routine isused to adjust layer transparency depending upon zoom layer.
 21. Themethod of claim 18 wherein the first map represents geographic featureslocated along a calculated route.
 22. A method of presenting a map on adisplay screen of a client computing platform, comprising the steps of:sending a request from the client computing platform to a server for mapdata; on the client computing platform, receiving map data from theserver, wherein the map data includes data from at least two separatelayers, wherein each of said layers represents geographic features at adifferent level of detail; using the map data from one of said layers topresent on a display screen of the client computing platform a first mapimage that represents geographic features in a first geographic area;initiating a zooming operation on the client computing platform; andpresenting an intermediate image on the display screen of the clientcomputing platform, wherein the intermediate image includes at least aportion of the first map image and also includes a second map image ofthe same geographic features shown in the portion of the first map imageusing data from another of said layers, wherein the same geographicfeatures shown by the first map image and the second map in theintermediate image coincide; after presenting the intermediate image,presenting an ending image on the display screen of the client computingplatform, wherein the ending image includes at least a portion of thesame geographic features shown in the first map image but at a differentscale and wherein the ending image is formed using data from a layerother than the layer used for forming the first map image.
 23. A methodof zooming a map on a computer display comprising: obtaining map data;using said map data for displaying representations of geographicfeatures on a display screen at a first scale with a first level ofdetail; displaying representations of at least some of the samegeographic features on the display screen at a second scale with asecond level of detail, wherein the second scale is different from thefirst scale and the second level of detail is different from the firstlevel of detail; and displaying an intermediate image after thedisplaying of the representations of the geographic features at thefirst scale and before the displaying of at least some of the samegeographic features at the second scale, wherein the intermediate imageis separate from said representation at the first scale and saidrepresentation at the second scale, wherein the intermediate imageoverlays representations of at least some of the geographic features attwo different levels of detail, wherein the two different levels ofdetail include one of: the first level of detail and the second level ofdetail, the first level of detail and a level of detail between thefirst level of detail and the second level of detail, and the secondlevel of detail and a level of detail between the first level of detailand the second level of detail.
 24. The method of claim 23 wherein thestep of obtaining comprises obtaining said map data from a server.